1. Field of the Invention
This invention relates to a control center and more particularly to insulated vertical bus bars having access openings with shutter means.
2. Description of the Prior Art
In a motor control center, the vertical bus bars distribute power to motor controllers arranged in a vertical stack, one above the other. The bus bars are often enclosed within insulating barriers to prevent accidental personal contact. However, the degree of safety offered by this means is considerably reduced by the need for access openings in the barrier at regular intervals. The openings are required in order to establish electrical connection between the individual controllers in a stack and the vertical bus bars, usually accomplished by a sliding stab connector. With the controller in its operating mode, there is complete safety, and no possibility of contact with the bus bars. With the controller withdrawn from its assigned space, however, the disconnect portion of the bus bar is clearly visible through the stab opening in the barrier, thus presenting a safety hazard. For example, reference is made to U.S. Pat. Nos. 3,096,131, 3,113,820, 3,170,092, and 3,840,785.
Manifestly, upon the withdrawal of a controller the openings may be closed by a suitable cover which can be placed manually. However, such a procedure per se presents a safety hazard.